Catheter

ABSTRACT

A catheter according to an embodiment of the present disclosure includes a mesh member, a first hollow shaft, a front end tip, a guiding film, a second hollow shaft, and a core wire. The mesh member has a tubular shape and is radially expandable and contractable. The guiding film is disposed on the mesh member and has a front end located between a base end of the front end tip and a front end of the first hollow shaft. A thickness of the front end of the guiding film is larger than a thickness of a portion where a thickness of the guiding film is the smallest.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of InternationalApplication No. PCT/JP2017/015958, filed Apr. 20, 2017. The content ofthis application is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a medical device, and specifically toa catheter.

BACKGROUND

Medical devices for removing a blood vessel-occluding blockage such aschronic total occlusion (CTO) to improve blood flow include, forexample, those in which mesh-like braided wires will be expandedradially at a site within a blood vessel where a blockage is present inorder to remove the blockage and those including a cover disposed over amesh-like self-expandable area so that a removed blockage can becollected, according to JP3655920 and JP2011-517424.

Nonetheless, such a blockage as described above may often be too hard tobe readily removed with the aforementioned medical devices. In such acase, the following have been proposed: a technology in which expansionof a false lumen is performed using an antegrade guide wire, and then aretrograde guide wire is passed through the expanded false lumen; and atechnology in which a mesh-like member is expanded so as to receive theabove guide wire through mesh openings thereof, according to document(Shinsuke Nanto, Ed. “Kakuzitsuni minitsuku PCI no kihon to kotsu,Revised edition,” Yodosha Co., Ltd., Feb. 25, 2016, pp. 222-227).

SUMMARY

However, the aforementioned mesh-like member may not be able to besufficiently expanded within a narrow blood vessel when the mesh-likemember is tried to be expanded, and thus may not necessarily be capableof reliably receiving a retrograde guide wire. Further, there aredemands for preventing breakage even if a retrograde guide wire isbrought into contact with a front end portion of a guiding film at ahigh load.

The present disclosure is made in view of the above circumstances. Anobject of the present disclosure is to provide a catheter including aguiding film capable of preventing breakage even if a retrograde guidewire is brought into contact with a front end portion at a high load.

To achieve the above object, a catheter according to an embodiment ofthe present disclosure includes: a mesh member having a tubular shapeand being radially expandable and contractable,

a first hollow shaft connected to a base end of the mesh member,

a front end tip connected to a front end of the mesh member,

a guiding film disposed on the mesh member, the guiding film having afront end located between a base end of the front end tip and a frontend of the first hollow shaft,

a second hollow shaft connected to the front end tip and disposed so asto protrude in a space inside the mesh member toward a base end side,and

a core wire having a front end connected to the front end of the meshmember and/or connected to the front end tip and extending inside themesh member and inside the first hollow shaft so that a base end of thecore wire is positioned at the base end side of the catheter relative toa base end of the first hollow shaft,

in which a thickness of the front end of the guiding film is larger thana thickness of a portion where a thickness of the guiding film is thesmallest.

It is noted that the term “front end side” as used herein refers to adirection where a front end tip is located relative to a mesh memberalong the longitudinal direction of a catheter. The term “base end side”refers to a direction which is opposite to the front end side along thatlongitudinal direction. The term “front end” refers to an end portion inthe front end side of each member of a catheter. The term “base end”refers to an end portion in the base end side of each member of acatheter. The term “maximum expansion diameter” refers to an outerdiameter at a portion where the outer diameter of a mesh member in adirection orthogonal to the axial direction is maximum in a state wherethe mesh member is expanded.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front elevational view of a first embodiment ofthe present disclosure in a state where a mesh member remains radiallycontracted;

FIG. 2 is a schematic front elevational view of a state where the meshmember of FIG. 1 is radially expanded;

FIG. 3 is a schematic perspective view of an example of an individualwire;

FIG. 4 is a schematic perspective view of another example of anindividual wire;

FIG. 5 is a schematic cross-sectional view of a state where the wiresshown in FIG. 4 are joined together;

FIG. 6 is a schematic cross-sectional view of a state where the wireshown in FIG. 3 and the wire shown in FIG. 4 are joined together;

FIGS. 7A and 7B are schematic cross-sectional views of differentexamples of a sealing member: in FIG. 7A, an end face has a curvedsurface; and in FIG. 7B, an end face has a planar surface;

FIG. 8 is a schematic front elevational view of an example of a statewhere the second hollow shaft shown in FIG. 1 is inclined;

FIGS. 9A and 9E are schematic views of joining regions between a corewire and a mesh member: in FIG. 9A, the joining region of a core wirehas a substantially ring-like shape; in FIG. 9B, the joining region of acore wire has a substantially C-like shape; and in FIG. 9C to FIG. 9E,the joining regions are each composed of a portion(s) of a substantiallyring-shaped article(s);

FIG. 10 is a schematic view of a different example of a junction betweena core wire and a mesh member;

FIG. 11 is a schematic view of the positional relationship between acore wire and the center of gravity of a front end tip on across-section along the XI-XI line in FIG. 1;

FIG. 12 is a schematic front elevational view of an example of a guidingfilm;

FIG. 13 is a schematic cross-sectional view cut along the XIII-XIII linein FIG. 12;

FIG. 14 is a schematic view of a preferred aspect of a guiding film;

FIG. 15 is a schematic view of another preferred aspect of a guidingfilm;

FIG. 16 is a schematic cross-sectional view of an example of the frontend portion of the guiding film in FIG. 15;

FIG. 17 is a schematic front elevational view of another example of thefront end portion of the guiding film in FIG. 15;

FIGS. 18A and 18B are schematic cross-sectional views cut along theXVIII-XVIII line in FIG. 17;

FIG. 19 is a schematic front elevational view of a modified example ofFIG. 1 in a state where a mesh member remains radially contracted;

FIG. 20 is a schematic front elevational view of a state where the meshmember of FIG. 19 is radially expanded;

FIG. 21 is a schematic front elevational view of the device of FIG. 2 inuse;

FIG. 22 is a schematic front elevational view of a second embodiment ofthe present disclosure in a state where a mesh member remains radiallycontracted;

FIGS. 23A and 23B are schematic cross-sectional views of holdingmembers: FIG. 23A shows one example and FIG. 23B shows another example;

FIG. 24 is a schematic front elevational view of another example of FIG.22 in a state where a mesh member remains radially contracted;

FIG. 25 is a schematic front elevational view of a state where the meshmember of FIG. 24 is radially expanded;

FIG. 26 is a schematic front elevational view of a modified example ofFIG. 22 in a state where a mesh member remains radially contracted;

FIG. 27 is a schematic front elevational view of a state where the meshmember of FIG. 26 is radially expanded;

FIG. 28 is a schematic front elevational view of a state where the meshmember of FIG. 22 is radially expanded;

FIG. 29 is a schematic front elevational view of a third embodiment ofthe present disclosure in a state where a mesh member remains radiallycontracted;

FIG. 30 is a schematic front elevational view of another example of FIG.29 in a state where a mesh member remains radially contracted;

FIG. 31 is a schematic front elevational view of a state where the meshmember of FIG. 30 is radially expanded;

FIG. 32 is a schematic front elevational view of a state where the meshmember of FIG. 29 is radially expanded, and an antegrade guide wire anda retrograde guide wire are inserted therethrough;

FIG. 33 is a schematic front elevational view of a catheter withouthaving the second hollow shaft shown in FIG. 1 in a state where a meshmember remains contracted; and

FIG. 34 is a schematic front elevational view of a state where the meshmember of FIG. 33 is radially expanded.

DETAILED DESCRIPTION

Below, the first to third embodiments of the present disclosure will bedescribed with reference to the figures, but the present disclosureshall not be limited to only the embodiments shown in the accompanyingfigures.

It is noted that among guide wires, the term “antegrade guide wire” asused herein means a guide wire to be pushed through toward an operationarea such as an occlusion site in a blood vessel prior to the presentcatheter. Among guide wires, the term “retrograde guide wire” means aguide wire approaching toward the present catheter from the front endside of the present catheter, for example, through a blood vessel.

First Embodiment

FIG. 1 is a schematic front elevational view of the first embodiment ofthe present disclosure in a state where a mesh member remains radiallycontracted. As shown in FIG. 1, a catheter 1 generally includes a meshmember 110, a first hollow shaft 120, a front end tip 130, a secondhollow shaft 140, a core wire 150, a guiding film 160, and a connector170.

The mesh member 110 is tubular, and capable of expanding and contractingin the radial direction. When the core wire 150 described below ispulled toward the base end side, the mesh member 110 undergoesout-of-plane deformation and inflates outwardly in the radial directionto expand radially, for example, as shown in FIG. 2. A retrograde guidewire is received into the catheter 1 through a mesh opening m of themesh member 110 which is radially expanded.

In the present embodiment, the mesh member 110 has a plurality of firstwires 111 and a plurality of second wires 112, and is configured so thatthe first wires 111 and the second wire 112 are braided into an overalltubular shape. Further, the mesh member 110 has a mesh opening m betweenadjacent braided wires, and receives a retrograde guide wire through themesh opening m which is enlarged upon radial expansion. It is noted thatthe front end tip 130 and the first hollow shaft 120 described below arejoined to the front end and the base end of each wire of the mesh member110, respectively.

Here, each wire of the mesh member 110 (the first wire 111 and thesecond wire 112) may be composed of either a solid wire a as shown inFIG. 3 or a plurality of wires. However, each wire may be formed of atwisted wire b in which a plurality of wires having different diametersfrom others are twisted. For example, a core wire b1 is centrallyarranged, and a plurality of side wires b2 are arranged so as tosurround the core wire b1 as shown in FIG. 4 (hereinafter, the firstwire 111 and the second wire 112 may be referred to as the first twistedwire 111 and the second twisted wire 112, respectively, when the twistedwire b as shown in FIG. 4 is used.). If that is the case, part of aplurality of wires of the first twisted wire 111 is preferably joined topart of a plurality of wires of the second twisted wire 112 (part of theside wires b2 in the present embodiment) at part of crossover portions110 a between the first twisted wire 111 and the second twisted wire 112as shown in FIG. 5. Alternatively, the mesh member 110 may include wiresin which the solid wire a is combined with the twisted wire b as shownin FIG. 6. In this case, the solid wire a is preferably joined to partof the plurality of wires of the twisted wire b (part of the side wiresb2 in the present embodiment) at part of the crossover portions 110 a.

When the first wire 111 and the second wire 112 are formed with thetwisted wires b as described above, the resulting mesh member 110 with atubular shape can have high deformability (flexibility), leading toimproved expandability of the mesh member 110. In addition, aconfiguration where part of the wires is joined as described above canprevent disentanglement of the first wire 111 and the second wire 112even if the mesh member 110 is excessively expanded, allowing for safeexpansion of the mesh member 110.

Further, the mesh member 110 has the maximum expansion diameter uponexpansion as shown in FIG. 2, and the number of joining regions disposedat a crossover portion 110 a between the first twisted wire 111 and thesecond twisted wire 112 is more preferably the smallest at a portionwhere the maximum expansion diameter is to be obtained. Specifically,the mesh member 110 is configured so that the number of the joiningregions 110 b in the circumferential direction on a cross section of aportion to have the maximum expansion diameter is smaller than thenumber of the joining regions 110 b in the circumferential direction ona cross section of the remaining portions. This can further improve theexpandability of the mesh member 110.

Further, the number of the joining regions 110 b in the circumferentialdirection disposed at the crossover portion 110 a between the firsttwisted wire 111 and the second twisted wire 112 also preferablyincreases toward both ends of the mesh member 110 (the front end andbase end of the mesh member 110). This can prevent disentanglement ofthe mesh member 110 from both ends, leading to improved expandabilityand robustness of the mesh member 110.

As a material of each wire of the mesh member 110, for example, a metalmaterial or a resin material may be used. Such metal materials include,for example, stainless steel such as SUS304, nickel-titanium alloys,cobalt-chromium alloys, and the like. Such resin material includes, forexample, polyamide, polyester, polyacrylate, polyetheretherketone, andthe like. Among these, metal materials are preferred in view of improvedstrength and flexibility. It is noted that the first wire 111 and thesecond wire 112, and the core wire b1 and the side wires b2 may beformed with the same material, or may be formed with differentmaterials.

Further, a radiopaque material is also preferably used as a material ofeach wire of the mesh member 110 in view of improving visibility of themesh member 110. Such radiopaque materials include, for example, gold,platinum, tungsten, or alloys including these elements (for example,platinum-nickel alloys and the like), and the like. It is noted that aradiopaque material may be combined with a material other than theradiopaque material, such as a composite where a radiopaque material iscoated on a non-radiopaque material.

The first hollow shaft 120 is connected to the base end of the meshmember 110. In the present embodiment, the first hollow shaft 120 has ahollow front end side shaft 121 having a front end connected to the baseend of the mesh member 110, and a hollow base end side shaft 123 havinga front end connected to a base end of the front end side shaft 121 asshown in FIG. 1.

The front end side shaft 121 has a lumen 122 in the inside thereof,through which a retrograde guide wire described below and the core wire150 can be inserted and passed. The base end side shaft 123 has a lumen124 in the inside thereof, through which the core wire 150 can beinserted and passed. Further, an opening 126 opening toward the base endside is formed at the base end of the front end side shaft 121 in aconnection portion 125 between the front end side shaft 121 and the baseend side shaft 123, and a retrograde guide wire will be directed to exitthe catheter 1 through the opening 126.

Here, a sealing member 127 having a hollow cylindrical shape ispreferably disposed inside the front end of the base end side shaft 123at the aforementioned connection portion 125 between the front end sideshaft 121 and the base end side shaft 123 so as to cover the outerperiphery of the core wire 150 and allow the core wire 150 to slide inthe axial direction thereinside as shown in FIG. 1. This can reduce agap between the outer periphery of the core wire 150 and the innerperiphery of the sealing member 127, preventing an end portion of aretrograde guide wire (not shown) from straying into the base end sideshaft 123. As a result, breakage of the first hollow shaft 120 and theretrograde guide wire can be prevented.

Further, the sealing member 127 as described above is preferablyconfigured to have a volume increasing from the front end toward thebase end side, and an end face 127 a of the front end side of thesealing member 127 is preferably inclined toward the opening 126.Specifically, the end face 127 a of the sealing member 127 is exposed tothe lumen 122, and configured to be inclined toward the opening 126 sothat a retrograde guide wire can pass through the opening 126 smoothly.This can prevent an end portion of a retrograde guide wire from beingcaught with the front end of the base end side shaft 123, enabling theretrograde guide wire to be easily guided to the opening 126. As aresult, breakage of the first hollow shaft 120 and the retrograde guidewire can be prevented. It is noted that as the sealing member, thefollowing may be used: a sealing member 128 shown in FIG. 7A in which anend face 128 a at the front end side has a curved surface, a sealingmember 129 shown in FIG. 7B in which an end face 129 a at the front endside has a planar surface perpendicular to the axial direction, and thelike.

There is no particular limitation for a material of the sealing member127 as long as the core wire 150 can slide thereon. Such materialsinclude, for example, resins such as polyamide resin, polyolefin resin,polyester resin, polyurethane resin, silicone resin, fluororesin,polyamide elastomer, polyolefin elastomer, polyester elastomer, andpolyurethane elastomer.

A material of the first hollow shaft 120 preferably hasantithrombogenicity, flexibility, and biocompatibility because the firsthollow shaft 120 is to be inserted into a blood vessel, and a resinmaterial or a metal material may be used. The front end side shaft 121,which needs to have flexibility, is preferably made of, for example, aresin material such as polyamide resin, polyolefin resin, polyesterresin, polyurethane resin, silicone resin, or fluororesin. The base endside shaft 123, which needs to have pushability, is preferably, forexample, a metal tube such as a hypotube.

The front end tip 130 is a member connected to the front end of the meshmember 110. Specifically, the front end tip 130 is configured to besharpened toward the front end side so that the catheter 1 can easilyadvance through the inside of a blood vessel. The front end portion ofeach wire of the mesh member 110 and the front end portion of the secondhollow shaft 140 described below are embedded in the base end portion ofthe front end tip 130.

A material of the front end tip 130 preferably has softness because thecatheter 1 is intended to advance through the inside of a blood vessel.Such materials having softness include, for example, resin materialssuch as polyurethane and polyurethane elastomer; and the like.

The second hollow shaft 140 is connected to the front end tip 130, anddisposed so as to protrude in a space inside the mesh member 110 towardthe base end side. As show in FIG. 1, the base end of the second hollowshaft 140 is located between the front end of the first hollow shaft 120and the base end of the front end tip 130 in the space inside the meshmember 110. In addition, the base end of the second hollow shaft 140 isconfigured to be separable from the core wire 150 without beingrestricted by the core wire 150. This configuration can allow the secondhollow shaft 140 to be inclined against the axial direction of the meshmember 110, and enables the base end of the second hollow shaft 140 topush the inner periphery of the mesh member 110 outwardly in the radialdirection as shown in FIG. 2 when the core wire 150 is pulled toward thebase end side. This can facilitate expansion of the mesh member 110.However, even if the second hollow shaft 140 is inclined, but does notabut on the inner periphery of the mesh member 110, the space inside themesh member 110 to be radially expanded can be expanded asymmetricallyas shown in FIG. 8. This can allow a retrograde guide wire to bereceived more easily.

A material of the second hollow shaft 140 preferably hasantithrombogenicity, flexibility, and biocompatibility because thesecond hollow shaft 140 is to be inserted into a blood vessel as in thefirst hollow shaft 120. Such materials include, for example, thoseexemplified in the description of the first hollow shaft 120, but resinmaterials are preferred in view of flexibility.

The core wire 150 is a member connected to the front end of the meshmember 110 and/or the front end tip 130, and extending through theinsides of the mesh member 110 and the first hollow shaft 120 so that abase end is positioned at the base end side relative to the base end ofthe first hollow shaft 120. Specifically, the core wire 150 extends tothe outside via a space outside the second hollow shaft 140 in theinside of the mesh member 110, the inside of the first hollow shaft 120,and then a through-hole 171 of the connector 170 (described below). Itis noted that the core wire 150 advances or retreats to radially expandor contract the mesh member 110 when the core wire 150 is operatedoutside the connector 170.

A material of the core wire 150 preferably has sufficient tensilestrength and stiffness in view of preventing breakage of the core wire150 itself and ensuring reliable expansion and contraction of the meshmember 110. Such metal materials include, for example, metal materialssuch as stainless steel such as SUS304, nickel-titanium alloys,cobalt-chromium alloys; and the like.

Here, the mesh member 110 and the core wire 150 are preferably formedwith a metal material(s), and the front end of the core wire 150 ispreferably located at the front end of the mesh member 110 in the axialdirection as shown in FIG. 9A. In addition, a joining region d ispreferably formed by joining the front end portion of the core wire 150and the front end portion of the mesh member 110. The joining region dformed as described above can strongly connect the mesh member 110 withthe core wire 150 to prevent detachment of the core wire 150 from themesh member 110 upon expansion of the mesh member 110.

It is noted that there is no particular limitation for thecross-sectional shape of the joining region d, but it is preferably asubstantially ring-like shape in which a hollow cylindrical member 153is joined to the core wire 150 (see FIG. 9A) or a substantially C-likeshape which is integrally formed with the core wire 150 (see FIG. 9B).Further, in view of improving plasticity of the front end tip 130 whenconnected to the front end tip 130, and in view of improving joiningstrength between the core wire 150 and the front end tip 130, thejoining region d may have the following structures: for example, astructure integrally formed with the core wire 152 (see FIG. 9C), astructure where a plurality of hollow cylindrical members 154 are joinedto the core wire 150 (see FIG. 9D), a structure where a hollowcylindrical member 155 having a cutoff portion is joined to the corewire 150 (see FIG. 9E), and the like. Further, the joining region d maybe arranged either on the outer periphery of the front end portion ofthe mesh member 110 (see FIG. 9A) or on the inner periphery of the frontend portion (see FIG. 10). This configuration can allow uniform force tobe applied to the front end portion of the mesh member 110 when the meshmember 110 is pulled toward the base end side, and thus enables the meshmember 110 to be more strongly connected to the core wire 150 withoutbreaking the mesh member 110 and the core wire 150.

It is noted that as shown in FIG. 11, a position p1 where a portion ofthe core wire 150 connected to the front end tip 130 and/or the meshmember 110 is projected on a cross section orthogonal to the axialdirection is preferably eccentric with respect to a position p2 wherethe center of gravity of the front end tip 130 is projected on the crosssection. However, the position p1 may be eccentric to a position wherethe center of gravity of the second hollow shaft 140 is projected on thecross section (not shown). This can allow the second hollow shaft 140 tobe easily inclined against the axial direction of the mesh member 110(i.e., can allow the second hollow shaft 140 to rotate around theaforementioned center of gravity) when the core wire 150 is pulledtoward the base end side to radially expand the mesh member 110. As aresult, the base end of the second hollow shaft 140 can easily bebrought into contact with the mesh member 110 to reliably press theinner periphery of the mesh member 110, facilitating radial expansion ofthe mesh member 110.

As shown in FIGS. 1 and 12, the guiding film 160 is arranged on the meshmember 110, and the front end of the guiding film 160 is located betweenthe base end of the front end tip 130 and the front end of the firsthollow shaft 120. The guiding film 160 is intended for smoothly guidinga retrograde guide wire received through the mesh opening m of the meshmember 110 toward the first hollow shaft 120. As shown in FIG. 13, theguiding film 160 according to the present embodiment is formed over themesh member 110 so as to bridge gaps between adjacent portions of thewires 111 and 112 at a region from a substantially central portion ofthe mesh member 110 in the axial direction where a front end is locatedthrough the front end of the first hollow shaft 120 where the base endof the guiding film 160 is located. Here, a retrograde guide wire may beguided into the first hollow shaft 120 through the mesh member 110 afterthe guiding film 160 is developed into a funnel shape upon radialexpansion of the mesh member 110. It is sufficient that at least aportion of the guiding film 160 (for example, the front end outerperiphery of the guiding film 160 and others) is joined to the meshmember 110. For example, the guiding film 160 may be a film-like member(not shown).

Materials which can be used for the guiding film 160 include, forexample, polyethylene, polyurethane, polyamide, polyamide elastomer,polyolefin, polyester, polyester elastomer, and the like. Among these,polyurethane is preferably used as the above material in view ofimproving surface slidability.

There is no particular limitation for a method of forming the guidingfilm 160, but the following may be used: for example, a dip method for aguiding film to be arranged on the mesh member 110; a method includingfusing the front end of a film with the mesh member 110 for a film-likeguiding film; and others.

Here, it is preferred that the guiding film 160 is formed with astretchable material, and arranged on the mesh member 110 so that afront end is located between the base end of the front end tip 130 andthe front end of the first hollow shaft 120, and the thickness of thebase end of the guiding film 160 is larger than that of the front end ofthe guiding film 160 (hereinafter, a guiding film having thisconfiguration may also be referred to as a “guiding film A”).The guidingfilm A as described above may be formed by removing a mesh member from adipping bath using the aforementioned dip method, and then allowing forcuring in a state where the base end side of the mesh member 110 isoriented vertically downward. This configuration where the guiding filmA has a thickness smaller at the front end than at the base end enablesthe mesh member 110 to be easily expanded. In addition, thisconfiguration where the guiding film A has a thickness larger at thebase end than at the front end can reduce the risk of breakage of theguiding film A upon contact with a retrograde guide wire.

It is noted that as shown in FIG. 2, the front end of the guiding film Ais also preferably located at a portion where the mesh member 110 showsthe maximum expansion diameter when the mesh member 110 is expanded.This enables maximum expansion of the guiding film 160 having afunnel-like shape, and thus a received retrograde guide wire can easilybe guided into the first hollow shaft 120.

Further, the thickness of the guiding film A also preferably increasesfrom the front end toward the base end (see to a continuous line and abroken line in FIG. 14). Moreover, it is also preferred that theexpansion diameter of the mesh member 110 decreases toward the base endfrom a portion of the maximum expansion diameter (see a dot-and-dashline in FIG. 14), and the thickness of the guiding film 160 increasestoward the base end from the front end in inverse proportion as theexpansion diameter of the mesh member 110 decreases (see the continuousline in FIG. 14). This enables the mesh member 110 to be easilyexpanded, and in addition can prevent breakage of the guiding film 160even if a retrograde guide wire is brought into contact with the baseend portion of the guiding film 160 at a high load.

Alternatively, it is also preferred that the guiding film 160 isarranged on the mesh member 110, and has a front end located between thebase end of the front end tip 130 and the front end of the first hollowshaft 120, and the thickness of the front end of the guiding film 160 islarger than that of a portion where the thickness of the guiding film160 is the smallest as represented by a continuous line and a brokenline in FIG. 15 (hereinafter, the guiding film of this configuration mayalso be referred to as a “guiding film B”).The guiding film B asdescribed above can be formed, for example, by producing a guiding film160 a having a uniform thickness, and then applying an overlay 160 b,which is made of a material for forming a guiding film, on the front endportion of the guiding film 160 a having a uniform thickness using aapplication method, thereby forming a guiding film 160, or by forming aguiding film using the aforementioned dip method, and then applying theoverlay 160 b as described above. This configuration where the thicknessof the front end of the guiding film 160 is larger than that of thethinnest portion can prevent breakage of the guiding film 160 even if aretrograde guide wire is brought into contact with the front end of theguiding film 160. Further, a similar effect can be also obtained whenthe thickness of the front end of the guiding film 160 is larger thanthat of other portions of the guiding film 160.

Furthermore, it is also preferred that as shown in FIG. 17, the guidingfilm B is provided to occlude part of a plurality of mesh openings mdefined between the first wire 111 and the second wire 112, and thefront end of a guiding film 161 is located at the crossover portion 110a between the first wire 111 and the second wire 112, and mesh openingsm1 and m2 circumferentially adjacent to the crossover portion 110 a areopened. In the aspect of the guiding film B as described above, the endportion of the guiding film 161 present within the mesh openings m isentirely edged with the wires (the first wire 111, the second wire 112)(the end portion of the guiding film 161 is entirely joined to thewires). This configuration can further reduce the risk of breakage ofthe guiding film 161, and can also prevent detachment of the guidingfilm 161 from the mesh member 110 even if a retrograde guide wire isbrought into contact with the front end of the guiding film 161.

Further, as shown in FIG. 18A, the thickness of the guiding film B isalso preferably the largest at the crossover portion 110 a between thewires 111 and 112. This configuration can reduce the risk of breakage ofthe guiding film 161 even if a retrograde guide wire is brought intocontact with the front end of the guiding film 161.

Moreover, the outer periphery of the crossover portion 110 a between thefirst wire 111 and the second wire 112 at the front end of the guidingfilm B is preferably covered with the guiding film 161 as shown in FIG.18B. This configuration can further reduce the risk of breakage of theguiding film 161, and can also prevent detachment of the guiding film161 from the mesh member 110 even if a retrograde guide wire is broughtinto contact with the front end of the guiding film 161.

As described above, the catheter 1 can easily and reliably guide aretrograde guide wire to the first hollow shaft 120 along the guidingfilm 160 by virtue of the guiding film 160 arranged on the mesh member110.

The connector 170 serves as a member with which an operator holds thecatheter 1. As shown in FIG. 1, the connector 170 is connected to thebase end of the first hollow shaft 120, and has the through-hole 171 incommunication with the lumens 122 and 124 of the first hollow shaft 120and an opening 172 formed at the base end of the through-hole 171. It isnoted that there is no particular limitation for the shape of theconnector 170, and any shape may be used as long as an operator caneasily hold it.

It is noted that as shown in FIGS. 19 and 20, the catheter 1 preferablyhas a marker 180 made of a radiopaque material and disposed at a portionof the core wire 150 which is to be positioned inside the front end ofthe guiding film 160 when the mesh member 110 is radially expanded, morepreferably when the mesh member 110 is radially expanded to an optimalextent. More preferably, the catheter 1 has the marker 180 and aradiopaque portion 160 a formed with a radiopaque material and disposedat the front end portion of the guiding film 160. The marker 180 ispreferably formed by, for example, mixing polyamide resin, polyolefinresin, polyester resin, polyurethane resin, silicone resin, fluororesin,or the like with a radiopaque material such as bismuth trioxide,tungsten, and barium sulfate when a resin material is used, orpreferably formed of, for example, gold, platinum, or tungsten as aradiopaque material, or an alloy containing any one or more of theseelements (for example, a platinum-nickel alloy and others) when a metalmaterial is used. The radiopaque portion 160 a is preferably formed bymixing a radiopaque material such as bismuth trioxide, tungsten, andbarium sulfate with a material with which the front end portion of theguiding film 160 is formed when a resin material is used as a radiopaquematerial, or preferably formed by joining gold, platinum, or tungsten asa radiopaque material, or an alloy containing any one or more of theseelements (for example, a platinum-nickel alloy and others) to the frontend portion of the guiding film 160 when a metal material is used. Thiscan allow the marker 180 and the front end of the guiding film 160 to beeasily recognized under fluoroscopy using radiations such as X-rays. Byvirtue of this, the mesh member 110 can be radially expanded to anoptimal extent by pulling the core wire 150 so that the marker 180 ispositioned inside the radiopaque portion 160 a at the front end of theguiding film 160. In addition, a retrograde guide wire can be easilyguided to the inside of the guiding film 160 using the radiopaqueportion 160 a as a visual clue, preventing contact between the guidingfilm 160 and the retrograde guide wire to prevent breakage of theguiding film 160. It is noted that the phrase “radially expanded to anoptimal extent” as used herein means that the mesh member 110 isradially expanded to the maximum extent within a range where no breakageof the guiding film 160 occurs due to excessive expansion so that aretrograde guide wire can easily be received.

Next, operating modes of the aforementioned catheter 1 will bedescribed. The catheter 1 can be used for not only receiving aretrograde guide wire W2 (Operating Mode 1) but also, for example,removing a blockage (Operating Mode 2). Below, Operating Modes 1 and 2will be described.

Operating Mode 1

In Operating Mode 1, the retrograde guide wire W2 will be received intothe catheter 1. In this Operating Mode 1, an antegrade guide wire W1(not shown) is inserted into, for example, a blood vessel, and thenpushed along the blood vessel to a site where a blockage is present(hereinafter may also be referred to as an “occlusion site”).

Next, after the front end of the antegrade guide wire W1 reaches theocclusion site, the base end of the antegrade guide wire W1 is insertedinto a through-hole at the front end of the second hollow shaft 140, andthen the front end of the catheter 1 is pushed to the occlusion sitethrough the blood vessel using the antegrade guide wire W1 as a guide.At this time, the catheter 1 in a state where the mesh member 110remains radially contracted is inserted into the blood vessel, and theabove radially contracted state is maintained until the front end of thecatheter 1 reaches the occlusion site.

Next, after the front end of the catheter 1 reaches the occlusion siteas described above, the antegrade guide wire W1 is withdrawn from thecatheter 1 by pulling the antegrade guide wire W1 toward the base endside with regard to the catheter 1. The core wire 150 exposed to theoutside of the connector 170 is then pulled toward the base end side toshorten the distance between the front end of the mesh member 110 andthe front end of the first hollow shaft 120. As a result of this, themesh member 110 undergoes out-of-plane deformation outwardly in theradial direction to expand radially. At this time, a mesh opening m isalso expanded as the mesh member 110 radially expands, creating acondition where the retrograde guide wire W2 can easily be received.Further, the second hollow shaft 140 which has been inclined pushes theinner periphery of the mesh member 110 outwardly in the radialdirection, facilitating radial expansion of the mesh member 110. It isnoted that in the present embodiment, the front end of the guiding film160 is joined to a substantially central portion of the mesh member 110in the axial direction, and thus the guiding film 160 expands radiallyas the mesh member 110 expands radially to form an overall funnel-likeshape.

Next, the retrograde guide wire W2 approaching toward the catheter 1from the front end side is received into the catheter 1 as shown in FIG.21. An approaching route of the aforementioned retrograde guide wire W2may likely be, for example, via a false lumen within a blood vessel wallsurrounding an occlusion site, a penetration-hole penetrating anocclusion site, or the like, but the retrograde guide wire W2 canapproach via any route. After received into a space inside the meshmember 110 through the mesh opening m of the mesh member 110 radiallyexpanded, the retrograde guide wire W2 is inserted into the front endside shaft 121 from an opening 120 a of the first hollow shaft 120, andthen directed to exit the catheter 1 through the opening 126. Theretrograde guide wire W2 which has exited the opening 126 is then passedthrough a blood vessel to exit the body. This can lead to a state wherethe retrograde guide wire W2 passes through the occlusion site, and bothends of the retrograde guide wire W2 are exposed to the outside of thebody.

As described above, the catheter 1, which can receive the retrogradeguide wire W2 and can guide the end portion thereof to the outside ofthe body, can be suitably used as a medical device for use incombination with the retrograde guide wire W2.

Operating Mode 2

In Operating Mode 2, the catheter 1 is used to remove a blockage withhelp from an antegrade guide wire W1 and others. In Operating Mode 2, amethod of inserting the antegrade guide wire W1 and the catheter 1, anda method of radially expanding the mesh member 110 are the same as themethods described above, and descriptions thereof will be omitted here.In Operating Mode 2, the antegrade guide wire W1 and the catheter 1 arefirst delivered to an occlusion site with the same procedure asdescribed in Operating Mode 1. The core wire 150 is then operated toradially expand the mesh member 110. It is noted that the antegradeguide wire W1 is not withdrawn from the catheter 1.

Next, a blockage is crushed using the antegrade guide wire W1 andothers. At this time, the crushed blockage is collected into a spaceinside the mesh member 110 through the mesh opening m of the mesh member110 radially expanded, and then guided into the first hollow shaft 120through the opening 120 a, and passed through the first hollow shaft 120to be discharged out of the body.

As described above, the catheter 1, which can be used to crush ablockage in a blood vessel and remove it out of the body, can be alsosuitably used as a medical device for removing a blockage.

As described above, the base end of the second hollow shaft 140 in thecatheter 1 configured as described above is separable from the core wire150 when the mesh member 110 is radially expanded by pulling the corewire 150 toward the base end side. This can allow the second hollowshaft 140 to push the inner periphery of the mesh member 110 tofacilitate expansion of the mesh member 110. Further, even if the baseend of the second hollow shaft 140 does not abut on the inner peripheryof the mesh member 110, the space inside the mesh member 110 to beradially expanded can be expanded asymmetrically so as to receive aretrograde guide wire more easily.

Second Embodiment

FIG. 22 shows a schematic front elevational view of the secondembodiment of the present disclosure in a state where a mesh memberremains radially contracted. As shown in FIG. 22, a catheter 2 generallyincludes the mesh member 110, the first hollow shaft 120, the front endtip 130, a second hollow shaft 240, a core wire 250, a holding member280, the guiding film 160, and the connector 170 (not shown). The secondembodiment differs from the first embodiment in that the secondembodiment includes the second hollow shaft 240, the core wire 250, andthe holding member 280. It is noted that the configurations of the meshmember 110, the first hollow shaft 120, the front end tip 130, theguiding film 160, and the connector 170 are the same as those of thefirst embodiment. Therefore, the same portions are designated with thesame reference numbers, and detailed descriptions thereof will beomitted. Further, the material(s) of the second hollow shaft 240 and thecore wire 250 is/are the same as that/those of the first embodiment.Therefore, descriptions in the first embodiment are referred to here,and detailed descriptions thereof will be omitted.

The second hollow shaft 240 is a member connected to the front end tip130, and disposed so as to protrude in a space inside the mesh member110 toward the base end side, and has a base end positioned between thefront end of the first hollow shaft 120 and the base end of the frontend tip 130.

The core wire 250 is a member having a front end connected to the frontend of the mesh member 110 and/or the front end tip 130 and a base endpositioned at the base end side relative to the base end of the firsthollow shaft 120, and extending along the outer periphery of the secondhollow shaft 240 and through the insides of the mesh member 110 and thefirst hollow shaft 120.

The holding member 280 has a substantially ring-like shape or asubstantially C-like shape in a cross-sectional view (see FIGS. 23A,23B), and is provided at the core wire 250 to cover the second hollowshaft 240. The holding member 280 covers the outer periphery of thesecond hollow shaft 240, and the second hollow shaft 240 can move in theaxial direction relative to the holding member 280. It is noted that inthe present embodiment, the holding member 280 is disposed so as tocover the base end of the second hollow shaft 240 as shown in FIG. 22,but may be disposed so as to cover a portion shifted toward the frontend side from the base end of the second hollow shaft 240 as shown inFIGS. 24 and 25 as long as the holding member 280 can prevent separationof the base end of the second hollow shaft 240 from the core wire 250 sothat they can be moved together.

It is noted that materials which can be used to form the holding member280 can include, for example, resin materials such as polyamide resin,polyolefin resin, polyester resin, polyurethane resin, silicone resin,and fluororesin, and metal materials such as stainless steel such asSUS304, nickel-titanium alloys, and cobalt-chromium alloys.

It is noted that the catheter 2 preferably has the holding member 280including a radiopaque material, and more preferably has the aboveholding member 280 including a radiopaque material and the radiopaqueportion 160 a formed with a radiopaque material and disposed at thefront end portion of the guiding film 160 as shown in FIGS. 26 and 27.When the holding member 280 is formed with a resin material as describedabove, for example, a radiopaque material such as bismuth trioxide,tungsten, and barium sulfate is preferably mixed with the holding member280. When the holding member 280 is formed with a metal material, forexample, gold, platinum, or tungsten as a radiopaque material, or analloy containing any one or more of these elements (for example, aplatinum-nickel alloy and the like), or the like is preferably used toform the holding member 280. The radiopaque portion 160 a is preferablyformed by mixing a radiopaque material such as bismuth trioxide,tungsten, or barium sulfate with a material with which the front endportion of the guiding film 160 is formed when a resin material is usedas a radiopaque material, or preferably formed by joining gold,platinum, or tungsten as a radiopaque material, or an alloy containingany one or more of these elements (for example, a platinum-nickel alloyor others) to the front end portion of the guiding film 160 when a metalmaterial is used. As shown in FIGS. 26 and 27, the holding member 280 inthe catheter 2 is preferably positioned inside the front end of theguiding film 160 when the mesh member 110 is radially expanded, morepreferably when the mesh member 110 is radially expanded to an optimalextent. This can allow the holding member 280 and the front end of theguiding film 160 to be easily recognized under fluoroscopy usingradiations such as X-rays. By virtue of this, the mesh member 110 can beradially expanded to an optimal extent by pulling the core wire 250 sothat the holding member 280 is positioned inside the radiopaque portion160 a at the front end of the guiding film 160. In addition, aretrograde guide wire can be easily guided to the inside of the guidingfilm 160 using the radiopaque portion 160 a as a visual clue, preventingcontact between the guiding film 160 and the retrograde guide wire toprevent breakage of the guiding film 160.

Next, how the catheter 2 works will be described. For example, thecatheter 2 is operated as in Operating Mode 1 described above to reachan occlusion site, and the core wire 250 is then operated to radiallyexpand the mesh member 110 as shown in FIG. 28. At this time, the secondhollow shaft 240, the base end of which is circumferentially coveredwith the holding member 280, is not inclined, and thus the second hollowshaft 240 is pulled toward the base end side along the axial directionto cause the mesh member 110 to expand radially without bringing thebase end of the second hollow shaft 240 into contact with the meshmember 110. This enables the retrograde guide wire W2 to be receivedthrough the mesh opening m of the mesh member 110.

According to the catheter 2 in which the second hollow shaft 240, thecore wire 250, and the holding member 280 are configured as describedabove, the holding member 280 can prevent separation of the base end ofthe second hollow shaft 240 from the core wire 250, enabling them to bemoved together. By virtue of the base end of the second hollow shaft 240not separated from the core wire 250, penetration of the guiding film160 by the second hollow shaft 240 can be prevented. It is noted thatwhen the outer periphery of the second hollow shaft 240 is covered withthe holding member 280, the configuration may be such that separation ofthe base end of the second hollow shaft 240 from the core wire 250 iswithin an extent where the base end of the second hollow shaft 240 isnot brought into contact with the guiding film 160.

Third Embodiment

FIG. 29 shows a schematic front elevational view of the third embodimentof the present disclosure in a state where a mesh member remainsradially contracted. As shown in FIG. 29, a catheter 3 generallyincludes the mesh member 110, the first hollow shaft 120, the front endtip 130, a second hollow shaft 340, the core wire 150, the guiding film160, and the connector 170 (not shown). The third embodiment differsfrom the first embodiment in that the third embodiment includes thesecond hollow shaft 340. It is noted that the configurations of the meshmember 110, the first hollow shaft 120, the front end tip 130, the corewire 150, the guiding film 160, and the connector 170 are the same asthose of the first embodiment, and thus the same positions aredesignated with the same reference numbers, and detailed descriptionsthereof will be omitted. Further, the material of the second hollowshaft 340 is the same as that in the first embodiment. Therefore,descriptions in the first embodiment are referred to here, and detaileddescriptions thereof will be omitted.

The second hollow shaft 340 is partially disposed in a space inside themesh member 110, and penetrates the mesh member 110 so as to positionthe base end thereof at the outside of the mesh member 110. It is notedthat the phrase “to position the base end thereof at the outside of themesh member 110” as used herein encompasses a case where a base end 341a of a second hollow shaft 341 is positioned at the outer periphery ofthe mesh member 110 as shown in FIGS. 30 and 31.

Here, both ends of the second hollow shaft 340 may be fixed to othermembers (for example, the front end tip 130, the mesh member 110, thefirst hollow shaft 120, and the like). However, it is preferred that thefront end of the second hollow shaft is connected to the front end tip130, and the base end of the second hollow shaft is free, or it ispreferred that the front end of a second hollow shaft is free, and theouter periphery of the base end portion of the second hollow shaft isconnected to the outer periphery of the mesh member 110 or the firsthollow shaft 120. This configuration where only one of the front end andthe base end portion of the second hollow shaft 340 is connected toanother member can prevent fracture of the second hollow shaft 340 whenthe mesh member 110 is expanded, and can ensure the passing ability ofthe antegrade guide wire W1 to allow procedures to be performed stablyand efficiently.

Further, the base end of the second hollow shaft 340 is preferablyopened toward the base end side. This allows the base end of theantegrade guide wire W1 to be directed to the base end side of thecatheter 3 through an opening at the base end of the second hollow shaft340 when the base end of the antegrade guide wire W1 is inserted intothe front end of the second hollow shaft 340 during procedures.Therefore, an operator can quickly recognize the position of the baseend of the antegrade guide wire W 1, and can easily and reliably holdthe base end portion of the antegrade guide wire W1. As a result ofthis, procedures can be performed efficiently using the catheter 3.

In the present embodiment, the catheter 3 has a configuration as shownin FIG. 29, in which the front end of the second hollow shaft 340 isfree, and the front end side of the second hollow shaft 340 is disposedin a space inside the mesh member 110. The second hollow shaft 340penetrates the mesh opening m of the mesh member 110 in a midway alongthe axial direction, and the base end of the second hollow shaft 340 ispositioned at the outside of the mesh member 110, and the outerperiphery of the base end portion is joined to the outer periphery ofthe first hollow shaft 120. An opening 340 a opening toward the base endside is disposed at the base end of the second hollow shaft 340.

It is noted that as shown in FIGS. 29 to 32, the catheter 3 preferablyhas the marker 180 made of a radiopaque material and disposed at aportion of the core wire 150 which is to be positioned inside the frontend of the guiding film 160 when the mesh member 110 is radiallyexpanded, more preferably when the mesh member 110 is radially expandedto an optimal extent. More preferably, the catheter 3 has the marker 180and the radiopaque portion 160 a formed with a radiopaque material anddisposed at the front end portion of the guiding film 160. For example,the configurations of the marker 180 and the radiopaque portion 160 amay be the same as that described in the first embodiment. This canallow the marker 180 and the front end of the guiding film 160 to beeasily recognized under fluoroscopy using radiations such as X-rays. Byvirtue of this, the mesh member 110 can be radially expanded to anoptimal extent by pulling the core wire 150 so that the marker 180 ispositioned inside the radiopaque portion 160 a at the front end of theguiding film 160. In addition, a retrograde guide wire can be easilyguided to the inside of the guiding film 160 using the radiopaqueportion 160 a as a visual clue, preventing contact between the guidingfilm 160 and the retrograde guide to prevent breakage of the guidingfilm 160.

Next, how the catheter 3 works will be described. For example, thecatheter 3 is operated as in Operating Mode 1 described above to reachan occlusion site, and the core wire 150 is then operated to radiallyexpand the mesh member 110 without withdrawing the antegrade guide wirefrom the second hollow shaft 340 as shown in FIG. 32. At this time, thebase end of the second hollow shaft 340 is positioned at the outside ofthe mesh member 110, and thus the antegrade guide wire W1 is not presentin the inside of the first hollow shaft 120. Therefore, the retrogradeguide wire W2, which is received through the mesh opening m of the meshmember 110 and inserted into the first hollow shaft 120, can smoothlyexit the opening 126 without occupying a space inside the first hollowshaft 120 simultaneously with the antegrade guide wire W1.

According to the catheter 3 including the mesh member 110, the front endtip 130, the second hollow shaft 340, and the guiding film 160configured as described above, the antegrade guide wire W1 does not passthrough the first hollow shaft 120. Therefore, the retrograde guide wireW2 can be directed to the first hollow shaft 120 while the antegradeguide wire W1 remains present in the second hollow shaft 340, allowingprocedures to be performed efficiently and simply.

It is noted that the present disclosure shall not be limited to theconfigurations of the aforementioned embodiments. All of alterationsmade within the scope of the claims and within the meanings and rangesequivalent to the scope of the claims are intended to be included. Atleast one of the configurations of the aforementioned embodiments may bedeleted or replaced by other configurations, or other configurations maybe added to the configurations of the aforementioned embodiments.

For example, the catheter 1 including the second hollow shaft 140 isdescribed in the first embodiment, but, for example, a catheter 4without the second hollow shaft 140 as shown in FIGS. 33 and 34 alsofalls within the scope intended for the present disclosure.

1. A catheter comprising: a mesh member having a tubular shape and beingradially expandable and contractable; a first hollow shaft connected toa base end of the mesh member; a front end tip connected to a front endof the mesh member; a guiding film disposed on the mesh member, theguiding film having a front end located between a base end of the frontend tip and a front end of the first hollow shaft; a second hollow shaftconnected to the front end tip and disposed so as to protrude in a spaceinside the mesh member toward a base end side of the catheter; and acore wire having a front end connected to the front end of the meshmember and/or connected to the front end tip and extending inside themesh member and inside the first hollow shaft so that a base end of thecore wire is positioned at the base end side relative to a base end ofthe first hollow shaft, wherein a thickness of the front end of theguiding film is larger than a thickness of a portion where a thicknessof the guiding film is the smallest.
 2. The catheter according to claim1, wherein the thickness of the front end of the guiding film is largerthan thicknesses of other portions of the guiding film.
 3. The catheteraccording to claim 1, wherein the mesh member includes a first wire anda second wire, the guiding film is provided to occlude part of aplurality of mesh openings defined between the first wire and the secondwire, and the front end of the guiding film is located at a crossoverportion between the first wire and the second wire, and mesh openingswhich are among the plurality of mesh openings and circumferentiallyadjacent to the crossover portion are opened.
 4. The catheter accordingto claim 3, wherein a thickness of the guiding film is the largest atthe crossover portion.
 5. The catheter according to claim 3, wherein anouter periphery of the crossover portion between the first wire and thesecond wire at the front end of the guiding film is covered with theguiding film.
 6. The catheter according to claim 1, wherein the portionwhere the thickness of the guiding film is the smallest is locatedbetween the front end of the guiding film and a base end of the guidingfilm along an axial direction of the catheter.
 7. The catheter accordingto claim 1, wherein the front end of the guiding film having the largerthickness is positioned at a portion where a maximum expansion diameteris obtained when the mesh member is expanded.